Carols, prayers and a speech from prime minister Tuilaepa Sailele Malielegaoi in the last hour of Thursday (local time) will move the country straight into Saturday.

"In doing business with New Zealand and Australia, we're losing out on two working days a week," the prime minister said, explaining the change.

"While it's Friday here, it's Saturday in New Zealand and when we're at church Sunday, they're already conducting business in Sydney and Brisbane."

Once the switch is made Samoa will be one hour ahead of Wellington and three ahead of Sydney.

The switch will reverse a decision made 120 years ago to move to the east of the international dateline because most of Samoa's trade at the time was with the United States and Europe.

Guests staying in Samoa's hotels this week will not be expected to pay for a day that does not exist, but employers must still pay staff for the Friday that never was.

Travel agent Velma Stambolis said Samoans were getting used to the idea.

"I think it should be a big celebration out there when it comes to the wake up on Saturday morning; oops it's Saturday morning now not Friday morning," she said.

"So it should turn out all right."

This is not the first significant change Mr Tuilaepa has introduced to Samoa, after switching driving from the right side of the road to the left in 2009 to bring the country in line with Australia and New Zealand.

His next target is changing Samoa's flag, a relic of the colonial era, but he has not yet disclosed what will be on the new flag.